Lamp socket



Jan. 19, 1960 ATTORN Ev.

United States Patent O LAMP SOCKET .lohn F. Corcoran, Newton, Mass.,assignor to United- Carr Fastener Corporation, Boston, Mass., acorporation of Delaware Application October 10, 1955, Serial No. 539,467

1 Claim. (Cl. 339-128) This invention relates generally to lamp socketsand has particular reference to a socket of the type which is adaptedfor assembly into a support panel opening.

Such installations are commonly provided in automotive lightingequipment in which a single wire is provided leading to the socket withthe support panel serving as the ground or return circuit. Sockets ofthis type are provided with spring means for biasing the contact againstthe terminal on the base of the bulb, and the contact and lead wire aredesigned to move rearwardly when the bulb is inserted to flex the springand thereby provide good electrical contact between the bulb and thelead wlre.

lt has been found that in some installations of this type the contact onthe end of the lead wire, or an exposed portion of the lead wireadjacent the contact can come in contact with the spring which resultsin a short circuit when the bulb is energized. Such short circuits havebeen more frequent in installations in which lead wires with certaintypes of plastic insulation are used. Since it has been found that whenthe wire is cut and the insulation trimmed to receive the contact, theinsulation tends to creep back on the wire leaving a considerableportion of the wire exposed adjacent the contact.

The object of this invention is to provide a lamp socket assembly inwhich means are provided to isolate the spring from the ground terminalof the socket.

A further object of the invention is to provide a lamp socket assemblyin which an insulating housing is provided with a bulb-receiving shellin the forward portion, a spring in the rear portion, and contactcarrying means disposed in the housing which also'serves to isolate theshell from the spring.

Other objects of the invention will, in part, be obvious, and will, inpart, appear hereinafter,

in the drawing:

Fig. l is a view in section partly in elevation of a lamp socketassembly embodying the features of the invention;

Fig. 2 is a view of the assembly of Fig. l with a lamp bulb, assembledtherewith;

Fig. 3 is a view in section taken on line 3--3 of Fig. l.

Referring to the drawing there is illustrated a lamp socket assembly 18which is adapted for assembly into an opening l2 in a support panel 14to receive a lamp bulb 16 from the opposite side of the panel.

The lamp socket comprises generally a housing 18 formed of insulatingmaterial having a rear end 20 with a central aperture 22, and aninternal circumferential groove 25 disposed medially thereon.

To provide means for receiving a lamp bulb base, a conductive shell 24is disposed in the forward portion 2,922,136 Patented Jan. 19, 1960 ofthe housing. The shell 24 in the illustrated embodiment is provided withJ-slots 26 to receive pins 28 on the lamp base in the usual manner, andhas axially extending spring ngers 30 for snapping engagement into thepanel aperture. The shell is retained in the housing by forwardly andoutwardly inclined tangs 32 projecting into the groove 25.

A coil spring 34 is provided in the rear portion of the housing whichrests against the rear end thereof, and an insulating washer 36 isdisposed on the forward end of the spring. The washer 36 is providedwith a central aperture 38 and a circumferential wall 40 which extendstoward the rear end of the housing beyond the end of the shell 24 andencloses the forward end of the spring.

The washer 36 is limited in its forward movement by radially inwardlyextending stop members 42 adjacent the rear end of the shell so that thespring is maintained in a partially compressed condition.

To complete an electric circuit to the bulb, a lead wire 44 extendsthrough the aperture 22 and the center of the spring, and is providedwith a contact rivet 46 on the end which has a head 48 disposed on theforward side of the washer and a shank 50 extending through the aperture38 of the washer.

When the lamp bulb is assembled into the socket the contact rivet andwasher are forced rearwardly compressing the spring 34. During suchassembly the lead wire must either move through the rear aperture 22, ormust ex sideways inside the housing. In the latter event it has beenfound that in some cases there is the possibility that the sidewaystiexing of the wire can cause tilting of the rivet to permit either therivet or the exposed portion of the wire to come in contact with thespring. However, the possibility of a short circuit by such contact iseliminated by the fact that the spring is isolated from the contact withthe shell by the insulating washer, and by the fact that the wall 40 ofthe washer tends to prevent tilting of the assembly in relation to theaxis of the socket.

The wall 40 also provides a smooth bearing surface to ride against theinner wall of the socket during assembly and removal of a lamp bulb.

Since certain obvious changes may be made in this device withoutdeparting from the scope of the invention, it is intended that allmatter contained herein be interpreted in an illustrative and not in alimiting sense.

I claim:

A lamp socket, comprising a housing formed of insulating material andhaving an opening at the forward end for receiving a lamp bulb, and anaperture in the rear end for receiving a lead wire, a conductive shelldisposed within the forward portion only of the housing and terminatingin substantial spaced relation to the rear end of the housing to providean exposed metal free inner wall of the housing between the end of theconductive shell and the rear end of the housing, said shell having-means for engaging and making electrical contact with the base of anassembled lamp bulb, and means projecting out of the forward opening formaking electrical contact with a ground panel, a contact-carrying washerof insulating material disposed in the housing, said wash er beingmovable longitudinally therein, and having a peripheral wall extendingtoward the rear of the housing and a coil spring disposed between therear end of the housing and the washer, the forward end of the springbeing enclosed by the peripheral wall, said shell having meansprojecting outwardly into engagement with the housing to retain theshell against longitudinal movement therein, and stop means near therear end of the shell projecting inwardly for engagement with theforward side of the Washer to limit the forward movement thereof onlypartly into said shell, said spring being retained under compressionbetween the Washer and the rear of the housing thereby being entirelyfree of any l,possille contact with the conductor shell.V

References Cited in the le of this patent UNITED STATES PATENTS KnaulMar. 26, 1918 Kent et al. Apr. 25, 1933 Mageoch et al June 14, 1949 DeReamer et a1 Oct. 2, 1951 Clayton Feb. 2, 1954 Cochran June 28, 1955

